Contracted Durability

A new white paper from RMI, Beyond Alliance, the American Forest Foundation, and LongRun Climate introduces contracted durability: a set of legal and financial mechanisms that ensure a carbon dioxide removal credit keeps one tonne of CO₂ out of the atmosphere across the durability threshold it is required to meet. Because no single pathway can deliver the volume of carbon removal that global climate goals require, contracted durability offers policymakers and standard setters a performance-based way to ensure every credit meets a clear durability requirement, enabling the full range of effective, high-integrity removal pathways to contribute.

Carbon dioxide removal (CDR) is not optional. Alongside rapid emissions reductions, CDR is essential to meeting global climate goals, including limiting near-term warming, achieving net-zero emissions, and ultimately drawing down the accumulated stock of carbon dioxide already in the atmosphere (IPCC AR6 Report, 2022). There are many pathways for removing and storing carbon but no single pathway is sufficient to meet the volumes of CDR required for net-zero or net-negative emissions; policymakers must therefore establish policies to support the full range of CDR pathways while ensuring verified climate impact.

Durability is one key determinant of that impact. ‘Durability’ refers to the length of time that a tonne of carbon dioxide (CO₂) represented by a CDR credit remains out of the atmosphere. However, durability is variable; not all credits represent CO₂ stored for the same duration. Durability is also uncertain, meaning the duration of storage is often unknown until a reversal (a net loss of CO₂ storage) occurs. This is particularly true for nature-based pathways, which capture and store CO₂ through naturally occurring biogenic carbon fixation. While capable of storing carbon for long timescales, these pathways face reversal risks such as wildfires, pests and disease, and human intervention.

The climate impact of carbon removal therefore depends on durability: i.e., how long CO₂ stays out of the atmosphere. Much of the policy debate around carbon removal has necessarily centered on durability. Establishing an appropriate durability threshold (i.e., the time period over which CO₂ must remain out of the atmosphere as defined by the policy, standard, use case, or claim being made) is a central concern, alongside defining how projects can reliably meet that threshold. Effective policy must support the full range of removal pathways while credibly managing variability and uncertainty in durability.

Contracted durability offers a way forward by using legal and financial mechanisms to ensure carbon removal over a defined duration. This paper introduces ‘contracted durability’ as a new concept that centers durability as an explicit, enforceable obligation at the credit level, fulfilling two core functions across the durability threshold: 1. assigning contractually enforceable liability for reversals, and 2. providing the resources and tools to compensate for any reversals that occur. Together, these functions ensure that one credit continues to represent one tonne of CO₂ removed from the atmosphere for the entirety of the required storage period — regardless of whether the original credit’s storage persists.

Policymakers designing carbon removal markets today have an opportunity to lay the groundwork for contracted durability — enabling the full range of CDR pathways to participate while ensuring that every credit delivers the climate impact it promises. Download the report for more information.

Additional Contributors: Kyle Clark-Sutton (RMI), Luke Pritchard (Beyond Alliance), Lyuba Tarnopolsky (CarbonPool), Nathan Truitt (American Forest Foundation)